Arrays of parallel terminal pins projecting from a support member find widespread use in many sophisticated electronic or solid state assemblies. In some instances, the arrays of terminal pins are utilized in the construction of printed circuit board assemblies. Such arrays of terminal pins are utilized to provide interconnections between different circuit paths formed on individual circuit boards that are laminated to provide a composite multi-layer board. The array of terminal pins on such circuit boards provide, or may provide, mountings for circuit components secured to the terminal pins. In other utilizations, the pins may provide the electrical connection between circuit paths on the board to wires laid and routed about and between the terminal pins.
In other instances, coordinate arrays of terminal pins are utilized in the manufacture of connectors wherein a coordinate array of pins project from a housing which contains a socket for receiving an end section of a circuit board having edge connectors or contacts. Groups of connectors of this type are often mounted in a common plane within a frame to form what is known as a backplane of an electronic or solid state equipment. One example of this type of equipment is the electronic switching frames presently being used in the telephone industry. When the connectors are mounted to form a backplane, the projecting terminals are utilized as the connect means to wired harnesses. In other instances, the terminals act as plugs on which backplane connectors are mounted to interconnect the terminal pins with other circuit assemblies.
Whether the arrays of terminals are to be wired or received in connectors, it is necessary that the terminals be straight and parallel. This requirement is particularly stringent when the wiring of the terminals is to be accomplished in an automatic wiring machine where wire routing and wrapping facilities depend upon the presence of straight parallel arrays of terminal pins.
One technique for straightening a coordinate array of pins contemplates bending the pins in a common direction beyond the elastic limit of the pin material, and then bending the pins in an opposite direction to again stress the pins beyond their elastic limits to impart a reset which is only sufficient to return the pins to straightened vertical positions when the pins are released. Subsequent thereto, bending forces may be applied in directions orthogonal to the first bending directions so that the rows and columns of pins are in an exact coordinate array.
Many equipments have been divised and are available to effectuate the reverse bending of arrays of terminal pins to attain a desired degree of straightness and alignment of the pins. An example of one such apparatus is disclosed in U.S. Pat. No. 3,730,234 issued May 1, 1973, to P. G. Hesselmann wherein an array of terminal pins extending through a printed circuit board are straightened by the reverse bending techniques. In the patented apparatus, a circuit board is supported in a tray having a floating lid in which there is formed an array of apertures corresponding to the array of terminals to be straightened. The terminals are received in the lid apertures and the tray is moved into a pin straightening machine whicn includes facilities for reciprocating the floating lid to bend the pins in opposite directions beyond the elastic limits. Next, the tray is withdrawn, rotated 90.degree. and then placed back in the machine where another bending cycle is executed to bend the pins in directions orthogonal to the first bending directions.
In general, these prior art terminal pin straightening techniques and devices execute cyclic bending in common directions; that is, all of the pins are bent in a first direction and then all of the pins are bent in a second, reverse direction. It is apparent that when the bending forces are applied in a common direction there are large forces imparted to the pin supports or mounting. If the terminal pins extend from a printed circuit board, there are tendencies to bend or bow the board. If the terminal pins extend from a connector housing, detrimental stresses are set up in the components of the connector housing.